[Python-checkins] [3.10] bpo-45773: Stop "optimizing" certain jump patterns (GH-29526)
brandtbucher
webhook-mailer at python.org
Thu Nov 11 16:52:48 EST 2021
https://github.com/python/cpython/commit/a89bbde83fe7f8cc347341e7ec57cda3ba312530
commit: a89bbde83fe7f8cc347341e7ec57cda3ba312530
branch: 3.10
author: Brandt Bucher <brandt at python.org>
committer: brandtbucher <brandtbucher at gmail.com>
date: 2021-11-11T13:52:43-08:00
summary:
[3.10] bpo-45773: Stop "optimizing" certain jump patterns (GH-29526)
files:
A Misc/NEWS.d/next/Core and Builtins/2021-11-09-13-01-35.bpo-45773.POU8A4.rst
M Lib/test/test_peepholer.py
M Python/compile.c
M Python/importlib.h
M Python/importlib_external.h
M Python/importlib_zipimport.h
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 4034154e4dcfb..11a4d1740b8dc 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -514,5 +514,12 @@ def test_bpo_42057(self):
except Exception or Exception:
pass
+ def test_bpo_45773_pop_jump_if_true(self):
+ compile("while True or spam: pass", "<test>", "exec")
+
+ def test_bpo_45773_pop_jump_if_false(self):
+ compile("while True or not spam: pass", "<test>", "exec")
+
+
if __name__ == "__main__":
unittest.main()
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-11-09-13-01-35.bpo-45773.POU8A4.rst b/Misc/NEWS.d/next/Core and Builtins/2021-11-09-13-01-35.bpo-45773.POU8A4.rst
new file mode 100644
index 0000000000000..2b9ba81be233f
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-11-09-13-01-35.bpo-45773.POU8A4.rst
@@ -0,0 +1 @@
+Fix a compiler hang when attempting to optimize certain jump patterns.
diff --git a/Python/compile.c b/Python/compile.c
index 90861038e07da..3eb34d89cc55f 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -21,6 +21,8 @@
* objects.
*/
+#include <stdbool.h>
+
#include "Python.h"
#include "pycore_ast.h" // _PyAST_GetDocString()
#include "pycore_compile.h" // _PyFuture_FromAST()
@@ -7264,25 +7266,24 @@ fold_rotations(struct instr *inst, int n)
}
}
-
-static int
-eliminate_jump_to_jump(basicblock *bb, int opcode) {
- assert (bb->b_iused > 0);
- struct instr *inst = &bb->b_instr[bb->b_iused-1];
- assert (is_jump(inst));
- assert (inst->i_target->b_iused > 0);
- struct instr *target = &inst->i_target->b_instr[0];
- if (inst->i_target == target->i_target) {
- /* Nothing to do */
- return 0;
- }
- int lineno = target->i_lineno;
- if (add_jump_to_block(bb, opcode, lineno, target->i_target) == 0) {
- return -1;
+// Attempt to eliminate jumps to jumps by updating inst to jump to
+// target->i_target using the provided opcode. Return whether or not the
+// optimization was successful.
+static bool
+jump_thread(struct instr *inst, struct instr *target, int opcode)
+{
+ assert(is_jump(inst));
+ assert(is_jump(target));
+ // bpo-45773: If inst->i_target == target->i_target, then nothing actually
+ // changes (and we fall into an infinite loop):
+ if (inst->i_lineno == target->i_lineno &&
+ inst->i_target != target->i_target)
+ {
+ inst->i_target = target->i_target;
+ inst->i_opcode = opcode;
+ return true;
}
- assert (bb->b_iused >= 2);
- bb->b_instr[bb->b_iused-2].i_opcode = NOP;
- return 0;
+ return false;
}
/* Maximum size of basic block that should be copied in optimizer */
@@ -7399,25 +7400,21 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
where y+1 is the instruction following the second test.
*/
case JUMP_IF_FALSE_OR_POP:
- switch(target->i_opcode) {
+ switch (target->i_opcode) {
case POP_JUMP_IF_FALSE:
- if (inst->i_lineno == target->i_lineno) {
- *inst = *target;
- i--;
- }
+ i -= jump_thread(inst, target, POP_JUMP_IF_FALSE);
break;
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
case JUMP_IF_FALSE_OR_POP:
- if (inst->i_lineno == target->i_lineno &&
- inst->i_target != target->i_target) {
- inst->i_target = target->i_target;
- i--;
- }
+ i -= jump_thread(inst, target, JUMP_IF_FALSE_OR_POP);
break;
case JUMP_IF_TRUE_OR_POP:
- assert (inst->i_target->b_iused == 1);
+ case POP_JUMP_IF_TRUE:
if (inst->i_lineno == target->i_lineno) {
+ // We don't need to bother checking for loops here,
+ // since a block's b_next cannot point to itself:
+ assert(inst->i_target != inst->i_target->b_next);
inst->i_opcode = POP_JUMP_IF_FALSE;
inst->i_target = inst->i_target->b_next;
--i;
@@ -7425,27 +7422,22 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
break;
}
break;
-
case JUMP_IF_TRUE_OR_POP:
- switch(target->i_opcode) {
+ switch (target->i_opcode) {
case POP_JUMP_IF_TRUE:
- if (inst->i_lineno == target->i_lineno) {
- *inst = *target;
- i--;
- }
+ i -= jump_thread(inst, target, POP_JUMP_IF_TRUE);
break;
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
case JUMP_IF_TRUE_OR_POP:
- if (inst->i_lineno == target->i_lineno &&
- inst->i_target != target->i_target) {
- inst->i_target = target->i_target;
- i--;
- }
+ i -= jump_thread(inst, target, JUMP_IF_TRUE_OR_POP);
break;
case JUMP_IF_FALSE_OR_POP:
- assert (inst->i_target->b_iused == 1);
+ case POP_JUMP_IF_FALSE:
if (inst->i_lineno == target->i_lineno) {
+ // We don't need to bother checking for loops here,
+ // since a block's b_next cannot point to itself:
+ assert(inst->i_target != inst->i_target->b_next);
inst->i_opcode = POP_JUMP_IF_TRUE;
inst->i_target = inst->i_target->b_next;
--i;
@@ -7453,54 +7445,33 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
break;
}
break;
-
case POP_JUMP_IF_FALSE:
- switch(target->i_opcode) {
+ switch (target->i_opcode) {
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
- if (inst->i_lineno == target->i_lineno) {
- inst->i_target = target->i_target;
- i--;
- }
- break;
+ case JUMP_IF_FALSE_OR_POP:
+ i -= jump_thread(inst, target, POP_JUMP_IF_FALSE);
}
break;
-
case POP_JUMP_IF_TRUE:
- switch(target->i_opcode) {
+ switch (target->i_opcode) {
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
- if (inst->i_lineno == target->i_lineno) {
- inst->i_target = target->i_target;
- i--;
- }
- break;
+ case JUMP_IF_TRUE_OR_POP:
+ i -= jump_thread(inst, target, POP_JUMP_IF_TRUE);
}
break;
-
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
- assert (i == bb->b_iused-1);
- switch(target->i_opcode) {
- case JUMP_FORWARD:
- if (eliminate_jump_to_jump(bb, inst->i_opcode)) {
- goto error;
- }
- break;
-
+ switch (target->i_opcode) {
case JUMP_ABSOLUTE:
- if (eliminate_jump_to_jump(bb, JUMP_ABSOLUTE)) {
- goto error;
- }
- break;
+ case JUMP_FORWARD:
+ i -= jump_thread(inst, target, JUMP_ABSOLUTE);
}
break;
case FOR_ITER:
- assert (i == bb->b_iused-1);
if (target->i_opcode == JUMP_FORWARD) {
- if (eliminate_jump_to_jump(bb, inst->i_opcode)) {
- goto error;
- }
+ i -= jump_thread(inst, target, FOR_ITER);
}
break;
case ROT_N:
diff --git a/Python/importlib.h b/Python/importlib.h
index dd1a9f172c04f..ab3e69b22b662 100644
--- a/Python/importlib.h
+++ b/Python/importlib.h
@@ -782,8 +782,8 @@ const unsigned char _Py_M__importlib_bootstrap[] = {
103,0,110,1,100,2,125,5,124,4,124,0,124,1,124,5,
100,4,141,3,83,0,124,3,100,2,117,0,114,67,116,0,
124,1,100,5,131,2,114,65,122,7,124,1,160,4,124,0,
- 161,1,125,3,87,0,110,13,4,0,116,5,121,64,1,0,
- 1,0,1,0,100,2,125,3,89,0,110,3,119,0,100,6,
+ 161,1,125,3,87,0,113,67,4,0,116,5,121,64,1,0,
+ 1,0,1,0,100,2,125,3,89,0,113,67,119,0,100,6,
125,3,116,6,124,0,124,1,124,2,124,3,100,7,141,4,
83,0,41,8,122,53,82,101,116,117,114,110,32,97,32,109,
111,100,117,108,101,32,115,112,101,99,32,98,97,115,101,100,
@@ -812,9 +812,9 @@ const unsigned char _Py_M__importlib_bootstrap[] = {
122,5,124,0,106,4,125,5,87,0,110,11,4,0,116,1,
121,59,1,0,1,0,1,0,100,0,125,5,89,0,110,1,
119,0,124,2,100,0,117,0,114,87,124,5,100,0,117,0,
- 114,85,122,5,124,1,106,5,125,2,87,0,110,13,4,0,
+ 114,85,122,5,124,1,106,5,125,2,87,0,113,87,4,0,
116,1,121,84,1,0,1,0,1,0,100,0,125,2,89,0,
- 110,3,119,0,124,5,125,2,122,5,124,0,106,6,125,6,
+ 113,87,119,0,124,5,125,2,122,5,124,0,106,6,125,6,
87,0,110,11,4,0,116,1,121,103,1,0,1,0,1,0,
100,0,125,6,89,0,110,1,119,0,122,7,116,7,124,0,
106,8,131,1,125,7,87,0,110,11,4,0,116,1,121,122,
diff --git a/Python/importlib_external.h b/Python/importlib_external.h
index 90c8d89d63074..bd4d95a61e00a 100644
--- a/Python/importlib_external.h
+++ b/Python/importlib_external.h
@@ -977,8 +977,8 @@ const unsigned char _Py_M__importlib_bootstrap_external[] = {
8,0,0,0,67,0,0,0,115,54,1,0,0,124,1,100,
1,117,0,114,29,100,2,125,1,116,0,124,2,100,3,131,
2,114,28,122,7,124,2,160,1,124,0,161,1,125,1,87,
- 0,110,38,4,0,116,2,121,27,1,0,1,0,1,0,89,
- 0,110,30,119,0,110,28,116,3,160,4,124,1,161,1,125,
+ 0,113,57,4,0,116,2,121,27,1,0,1,0,1,0,89,
+ 0,113,57,119,0,110,28,116,3,160,4,124,1,161,1,125,
1,116,5,124,1,131,1,115,57,122,9,116,6,116,3,160,
7,161,0,124,1,131,2,125,1,87,0,110,9,4,0,116,
8,121,56,1,0,1,0,1,0,89,0,110,1,119,0,116,
@@ -990,7 +990,7 @@ const unsigned char _Py_M__importlib_bootstrap_external[] = {
1,83,0,124,3,116,16,117,0,114,131,116,0,124,2,100,
6,131,2,114,130,122,7,124,2,160,17,124,0,161,1,125,
7,87,0,110,9,4,0,116,2,121,124,1,0,1,0,1,
- 0,89,0,110,10,119,0,124,7,114,130,103,0,124,4,95,
+ 0,89,0,113,134,119,0,124,7,114,130,103,0,124,4,95,
18,110,3,124,3,124,4,95,18,124,4,106,18,103,0,107,
2,114,153,124,1,114,153,116,19,124,1,131,1,100,7,25,
0,125,8,124,4,106,18,160,20,124,8,161,1,1,0,124,
diff --git a/Python/importlib_zipimport.h b/Python/importlib_zipimport.h
index bb870c3a0353a..07c9dd574040f 100644
--- a/Python/importlib_zipimport.h
+++ b/Python/importlib_zipimport.h
@@ -1004,9 +1004,9 @@ const unsigned char _Py_M__zipimport[] = {
1,0,1,0,89,0,113,9,119,0,124,8,100,4,25,0,
125,9,116,8,124,0,106,4,124,8,131,2,125,10,100,0,
125,11,124,5,114,91,122,10,116,9,124,0,124,9,124,7,
- 124,1,124,10,131,5,125,11,87,0,110,25,4,0,116,10,
+ 124,1,124,10,131,5,125,11,87,0,113,96,4,0,116,10,
121,90,1,0,125,12,1,0,122,8,124,12,125,3,87,0,
- 89,0,100,0,125,12,126,12,110,10,100,0,125,12,126,12,
+ 89,0,100,0,125,12,126,12,113,96,100,0,125,12,126,12,
119,1,119,0,116,11,124,9,124,10,131,2,125,11,124,11,
100,0,117,0,114,101,113,9,124,8,100,4,25,0,125,9,
124,11,124,6,124,9,102,3,2,0,1,0,83,0,124,3,
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